Heather Kiessling - 01 Jul 2026 Form 4 Insider Report for ASP Isotopes Inc. (ASPI)

Reporting relationship: Chief Financial Officer
Issuer ticker: ASPI
Reported as of: 01 Jul 2026
Net transaction value: -$145,219
SEC form: 4
Accepted by SEC: 02 Jul 2026, 21:45:24 UTC
Prior SEC filing: 03 Jun 2026
Source filing: View source filing
Reporting owner signature: /s/ Donald Ainscow, as attorney-in-fact

Key filing fact

Heather Kiessling filed Form 4 for ASP Isotopes Inc. (ASPI) on 02 Jul 2026.

Key facts

This page summarizes Heather Kiessling's Form 4 filing for ASP Isotopes Inc. (ASPI).
1 reported transaction and 0 derivative rows are listed below.
Accepted by SEC: 02 Jul 2026, 21:45.

Change

Previous filing in this sequence was filed on 03 Jun 2026.
Current net transaction value: -$145,219.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002026548 Primary reporting owner

Kiessling Heather

Relationship: Chief Financial Officer
Address: C/O ASP ISOTOPES INC., 2200 ROSS AVENUE, SUITE 4575E, DALLAS
Signature: /s/ Donald Ainscow, as attorney-in-fact
Signature date: 02 Jul 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

ASPI transaction

Common Stock

Sale

Transaction value: $145,219
Shares: -23,124
Change %: -1.5%
Price: $6.28
Shares after: 1,526,252
Date: 01 Jul 2026
Ownership: Direct
Footnotes: F1, F2

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 2 footnotes

Footnote F1

Represents "sell to cover" sales effected pursuant to a Rule 10b5-1 trading plan adopted by the filing person on December 19, 2025 to cover tax withholding obligations in connection with the quarterly vesting of a restricted stock award.

Footnote F2

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $6.13 to $6.52, inclusive. The reporting person undertakes to provide ASP Isotopes Inc. (the "Company"), any stockholder of the Company, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote.